1) Field
Embodiments relate to the field of semiconductor processing and, in particular, to devices and methods for measuring material deposition or material removal in a wafer processing tool.
2) Description of Related Art
A primary concern in the manufacture of semiconductor devices is particle contamination of a semiconductor wafer. Such contamination typically occurs during one or more operations performed by a wafer processing tool during manufacture of the semiconductor devices. For example, the wafer processing tool may include several interfaces, e.g., several chambers interconnected by load locks, and the actuation or operation of any of these system components may generate metallic or nonmetallic particles such as aluminum, stainless steel, zirconium, or other particles that can contaminate a semiconductor wafer in the tool. One skilled in the art will appreciate that particles may come from many sources within the wafer processing tool other than interfaces and moving parts, and thus, the above is provided by way of example.
To identify a source and/or root cause of particle contamination, semiconductor wafers are periodically processed through one or more chambers of the wafer processing tool and then subjected to a particle inspection operation. The particle inspection operation requires the processed wafer to be queued for inspection by optical inspection equipment to identify a location and general size of particles, and then queued for inspection by scanning electron microscopy, energy dispersive spectroscopy, or other inspection techniques to determine a presence and/or composition of particles on the wafer. After detecting the presence and composition of the particles, additional troubleshooting may be required to identify which of the operations performed by the wafer processing tool actually led to the particle contamination.
The manufacture of semiconductor devices may involve the deposition and removal of material, and more particularly semiconductor material, on a substrate by the wafer processing tool using, e.g., deposition or etching processes. To accurately deposit or remove a specified amount of semiconductor material, film thickness measurement techniques may be used. For example, material deposition and material removal rates may be indirectly measured by processing a wafer of semiconductor material for a given amount of time, and then measuring an amount of film deposited or removed using an ellipsometer. Furthermore, sensors have been used to measure secondary factors that correlate with deposition/removal rates to indirectly estimate deposition/removal rates during a wafer fabrication process.